Dysprosium radioactive elements

The third place is held by France where fifteen elements were discovered chromium (1797), beryllium (1798), boron (1808), iodine (1811), bromine (1826), gallium (1875), samarium (1879), gadolinium (1886), dysprosium (1886), radium (1898), polonium (1898), actinium (1899), europium (1901), lutecium (1907), francium (1939). It is not surprising that the radioactive elements polonium, radium, and actinium were discovered by French scientists. These discoveries proceeded from the pioneering studies of radioactivity conducted in France. A brilliant spectral analyst P. Lecoq de Boisbaudran discovered by means of spectral analysis four new elements—gallium and three rare-earth elements (samarium, gadolinium, and dysprosium). Chromium and beryllium were discovered by L. Vauquelin who was such a skillful analytical chemist that it would be unjust if he had not given the world at least one new element. 

G. Hevesy and H. Levi, Artificial radioactivity of dysprosium and other rare earth elements, Nature 136 (1935) 103. G. Hevesy and H. Levi, Action of slow neutrons on rare earth elements, Nature 137 (1936) 185. 

Samples (156) were taken from 54 reference lithic pieces that represented five rock types. These samples were analyzed at the SLOWPOKE Reactor Facility of the University of Toronto. They were irradiated for 1 min at 2 kW, or for 1 or 2 min at 5 kW (depending on their radioactivity level in preliminary tests). Upon removal from the reactor, the samples, which weighed between 0.1 and 0.3 g, were left to decay for 18 min and were counted for 5 min with a Ge(Li) y-ray detector coupled to a multichannel analyzer. Trace element concentrations were calculated with the comparator method (7). The 15 elements examined were barium, titanium, sodium, aluminum, potassium, manganese, calcium, uranium, dysprosium, strontium, bromine, vanadium, chlorine, magnesium, and silicon. The first seven of these elements were the most useful in the differentiation of major rock types. 

The identification of element 98 was accomplished with a total of only 5,000 atoms (Thompson et al. 1950b). The ion-exchange techniques were also used in the separation and identification of californium. Element 98 was eluted in the expected fraction, and the observed half-life and ot-particle energy of the radioactivity were also in agreement with predictions. It was named after the state of its discovery, although the chemical analog of element 98 was dysprosium (Dy). 

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